This invention, in one of its aspects, pertains to external cargo carriers for helicopters. In a more specific aspect the invention relates to sling carriers capable of carrying motorized vehicles. Even more specifically, the invention is concerned with devices empowering multiple motorized vehicle lifts.
In external cargo carrying helicopters single or multiple point suspension cargo slings are attached to cargo hooks on the undersides of helicopter fuselages, generally positioned relative to the center of gravity of the helicopter. It is common practice to use such helicopters to transport motorized vehicles to the front, for assault and retrograde operations, or to an area where maneuvers are being conducted. However transporting such vehicles presents a rigging challenge, even in the case of smaller vehicles such as jeeps and automobiles. Large vehicles such as tanks and high mobility, multipurpose, wheeled vehicles (HMMWVs) are an even greater challenge. Moreover this method of transporting such vehicles is frequently impractical, either because of the excessive number of sorties necessary to transport the vehicles, or the limited number of available aircraft.
The Chinook was brought into service with the thought the HMMWVs could be carried inside them, but the HMMWVs were too wide to be easily loaded inside its fuselage. Hence sling loading still must be employed even with the Chinook, using its dual tandem cargo hook suspension system. However with helicopters capable of carrying heavier loads multiple lifts are being considered. With the Chinook it is possible to carry two HMMWVs instead of one, as in the case of the Black Hawk. But in carrying two vehicles, rigging is even more difficult. In a helicopter cargo carrying environment there are so many force components and degrees of movement that vertical, lateral, and rotational moments are difficult to control. Because of these moments a simple tow bar cannot be used. It simply would not restrain rotational forces. The use of two cargo hooks prevents the load from revolving. Nevertheless the rotational component still introduces a jack knifing effect. Hence rigging so that the system is stable is not a simple matter in any case in which a heavy load is swinging from the bottom of a helicopter. In the case of two vehicles, which must be carried so that they will not bump against each other, rigging is particularly challenging. Bending moments must be considered in addition to vertical, horizontal, and rotational forces.
As pointed out in the Department of Navy report NSAP Task Q-1-85, RW-2R-86, attachment of vehicles in tandem to a single rigid lift beam under helicopters would require a beam of such large dimensions that operation and stowage requirements could not be met. Accordingly, as described in the report, the vehicles are carried side-by-side. Positioning or spreader bars were installed laterally across the HMMWV's forward and aft sling points, providing lateral vehicle separation. This loading has the disadvantage that excessive lateral motion can still cause vehicle damage. In fact cylindrical hood protectors are suggested to preclude hood or windshield damage. In addition the device described in the report cannot be used on automobiles and jeeps not equipped with sling points on their hoods and trunks. By the practice of this invention a cargo adapter is provided which is so constructed that the two vehicles being carried can not bump against each other during flight. The tandem positioning unit provided herein does not require special hood and trunk attachment points, and, therefore, can be used with jeeps and automobiles. In addition the tandem action resulting causes the vehicles to act as one while in flight.